CIRCUIT DESCRIPTION
THEORY OF OPERATION
AS SHOWN IN THE BLOCK DIAGRAM, THIS MIXER HAS 5 INPUTS AND 3 OUTPUTS.
THE DC
15V
POWER SUPPLY ENABLES THE
18V/AC
ADAPTOR TO BE CONVERTED TO
±15V
/DC AND IS USED TO FEED THE
IC
OF EACH STAGE AND LAMP OF THE VU METER.
THE MIC SIGNAL FROM INPUT JACK THROUGH
MIC
AMPLIFIER
(IC2
IS A LINEAR AMP-
LIFIER) MAGNIFICATION, THEN SEND TO THE MIC LEVEL
CONTROL(VRl),
AFTERWARD,
THE MIC SIGNAL IS SEND TO THE MIXING BUS. AND THE
PHONO
l(IC3.VR2)/PHONO
2
(IC4/VR3)
LIKEWISE.
(IC3/IC4
IS A MATCH TO RIAA CURVES UNLINEAR AMPLIFIER)
THE SIGNAL OF
CDl/VIDEO
FROM INPUT JACK IS DIRECTLY SEND TO THE LEVEL
CON-
TROL(VR4),
THEN SEND TO THE MIXING BUS. AND
CD2/LINE
LIKEWISE.
THE SIGNAL OF MIXING BUS GOES TO THE WEIGHTED SUMMING AMPLIFIER(IC6) AND
THEN ON TO THE MASTER GAIN STAGE(IC1) MAGNIFYING IT WHICH RESULTS AS OUT-
PUT GOING TO THE REC OUTPUT JACKS AND THE MASTER OUTPUT STAGE
(IC5),
AND
THE MASTER OUTPUT STAGE(IC5 IS A LINEAR AMPLIFIER) SEND THE OUTPUT SIGNAL
TO THE OUTPUT JACKS.
THE SIGNAL COMING FROM THE MASTER OUTPUT STAGE(IC5) GOES THROUGH THE VU
METER
AMPLIFIER(IC7),
WHICH IS THEN SHOWN ON THE VU METER.
THE SIGNAL(PRE-FADE)
OF EA
C
H
CHA
N
NELS
GO
ES
THROUGH
THE
MONITOR
SELEC
T
swI-
TCH (ROTARY SWITCH
SW1)WHICH
IS THEN TRANSMITTED TO THE HEADPHONE
AMPLIFI-
ER(IC8)
&
MAGNIFIED,THEN GOES TO THE HEADPHONE JACK.
